DE602004011534T2 - TRANSMIT APODISER CONTROL FOR MICRO-STROKE SHAPERS - Google Patents

Abstract

Apodization control techniques for a microbeamformer including a plurality of microbeamformer channels each including a transducer, a microbeamformer transmitter for driving the transducer, a microbeamformer receiver for receiving signals from the transducer and usually a delay element for delaying the received transducer signals. To improve the generation of waveforms by the transducers, the voltage provided to the microbeamformer transmitters is adjusted and/or the current provided by the microbeamformer transmitters is adjusted. The microbeamformer channels can also be grouped together into patches and/or clusters with the patches and clusters being provided with a common voltage source or current.

Description

The The present invention relates generally to an ultrasonic transducer for the medical imaging, and more particularly to a system for apodization control in an ultrasonic transducer, d. H. for controlling the shape of the transmission beam of a Ultrasonic transducer, primarily in the context of a sub-array beam shaping.

Subarray beamforming or microbeamforming involves the use of transmit and / or receive arrays of ultrasound transducers grouped into subarrays. In the U.S. Patent 5,997,479 For example, an application of microbeamforming is described in which a plurality of transducer elements are grouped into different transmit subarrays, and a receive array comprises a plurality of transducer elements grouped into different receive subarrays. 2 the patent 5997479 Figure 12 also shows various in-group transmit processors connected to the transmit sub-arrays and generating an acoustic transmit beam directed to the region of interest, as well as various in-group receive processors connected to the receive sub-arrays. Each in-group receive processor is adapted to receive transducer signals from the transducer elements of the connected sub-array in response to echoes from the acoustic transmit beam. Each in-group receive processor includes delay and summation elements that delay and sum the received transducer signals. A receive beamformer includes various processing channels connected to the in-group receive processors, and each processing channel includes a beamformer delay that synthesizes received beams from the echoes by delaying received signals from the in-group receive processor and a beamformer summer that delays signals received from the processing channels and summed up.

In addition, in the U.S. Patent 6,013,032 another microbeamformer is described in which each subarray of the transducer array is connected to a subarray beamformer, each subarray beamformer comprising a subarray processor and a phase shift network connected to the output of the subarray processor (see 2 and their description). A primary beamformer includes a summing unit which sums the outputs of the beamformer channels to which the output of the subarray beamformers is applied, thereby providing a beamformer signal representative of the received ultrasonic energy along a desired scanline.

Of the hereinafter commonly used term describes microbeamformer a sub-array beam shaper that integrates into the handle of the transducer is to connect to a very large number of piezoelectric To facilitate sensor elements in a two-dimensional array are arranged. Such a configuration allows the real-time volumetric imaging when combined with a Mainframe beamformer and a downstream display subsystem is used. Instead of the electronics of the subarray beamformer to integrate in the handle of the converter, it can be in the mainframe be arranged. The term micro-beam shaping could also for one-dimensional Arrays are used.

at the micro-beam shaping is the control of the shape of the transmission beam important aspect for successful implementations of multi-line imaging converters, especially in real-time volume acquisition, where multi-line, higher-order imaging is required to achieve adequate volume acquisition rates. A Control of the shape of the transmitted beam is possible because in current Ultrasonic transducers typically convert each element in the transducer array Connected to a control electronics, so that each element is individually controllable.

Further can be used in micro-beamforming and other beamforming applications, which comprise a transducer array, always only part of the total number of elements in the transducer array at the same time be. This is referred to as control of the aperture of the transducer array. The Aperture of the transducer array refers to the configuration of the Transducer elements that are active at any one time. The electronic control of each element in the converter makes it possible to shape and delay the transmit and receive signals a suitable signal for the type of each performed To deliver imaging.

Referring to 8th Microbeamformers are commonly used with a variety of microbeamformer patches 100 constructed with each microbeamformer patch (or subarray) 100 at least one and often multiple microbeamformer channels 102 includes. Each microbeamformer channel 102 is with a converter 106 and includes a microbeamformer transmitter 104 for driving the converter 106 and a microbeamformer receiver 108 for receiving the signals from the converter. Preferably also a delay element 110 provided to delay the received transducer signals, and a control circuit 122 to the transmitter 104 to stimulate. Further details about the operation of microbeamformer channels can be found in the above-mentioned patents. Thus, the Mikrostrahlformer has individual Transmitter for each microbeamformer channel 102 to provide a beam steering and focusing control. Although additional channels are usually on the mainframe 112 are provided, these mainframe transmitters are not used to the converter 106 head for. Instead, there are between the recipients 116 on the mainframe 112 and the microbeamformer patches 102 coaxial 114 connected so that the coaxial cable 114 only for the receive path and not for the transmit path. Via a coaxial cable 120 is a single energy supply 118 with all microbeamformer patches 100 coupled.

For a microbeamformer, like the one in 8th It is known that, by controlling the time interval and the transmission energy supplied to some or all of the microbeamformer channels (generally referred to as "transmit beamforming"), the ultrasound polling pulse transmitted to an object being examined may be shaped, for example, at different depths Similarly, the received energy can be used to produce high quality images at various depths by electronically modifying the receive weights and delays (referred to as "receive beamforming").

A The way to control the transducer elements is known as apodization. The apodization of an ultrasonic transducer aperture is a gradual reduction the transmit amplitude and / or receive gain from the center to the edges the aperture with a resulting reduction in beam lobe levels.

In In practice, different apodization methods are used. For example, the use of rectangular pulse generators is known with supply voltages over the active aperture will vary as well as the application of a channel wise one Apodization with the help of wave transmitters. Is achieved through this ability additional complexity either in the power management components or the individual transmitters.

At the Design of microbeamformers for Real-time 3D imaging is of particular importance because of the integrated circuits (ICs) of the micro-beam former in the Handle of the converter must fit. Furthermore must because of the difficulty, for the cooling micro-beamformer electronics, which limits power dissipation become. The transmitter in the Mikrostrahlformer should as such a possible have simple and elementary construction, and a complicated one Modification of the transmitter to provide the apodization should be avoided.

The Microbeamformer ICs in a prior art system use unipolar pulse generators that each have two apodization levels per element Provide: on or off. This system has the disadvantages that apodization is limited and there is often insufficient beam lobe control provides. It would be therefore advantageous, new methods for Apodisierungssteuerung for sending of micro-beam shapers that enable suitable beam lobe control, without the circuitry that needs to be housed in the transducer handle, significantly complicate.

Around to control the acoustic signal generated by the transducers of some prior art ultrasound imaging systems the array elements in the converter with a simple boxcar voltage excitation signal driven by different duration and with different duty cycle. The skilled person is aware of how these voltage excitation signals generated at a fixed or variable mainframe power supply become. Frequently becomes the voltage or pulse width changed to try that Amplitude of the acoustic signal to change. By changing the Drive voltage changes the total energy provided to drive the converter can be while by changing the pulse width of the driving voltage changes the way as the transducer resonates, with different acoustic signal amplitudes possible are. It works for purposes of apodization across an array good for Each converter to have different drive voltages. However, in those driving units, the low voltages the driver circuits themselves convert a lot Energy around, because the output voltage and the high voltage bus of the Systems can be very different. For microbeamformers can this inefficiency (due to the associated probe heating) can not be tolerated, so it would be beneficial to have an efficient driving method to create different output voltage pulses.

Around To generate a square-wave voltage pulse to the converter must be Transmit or subtract significant amounts of electricity to charge the capacity connected to the converter. Unfortunately, that is Current through pull-up and pull-down MOSFET devices directly proportional to their width, so that a very large (wide) component required is to big streams provide or subtract. There's room in microbeamformers of highest importance is, would be it is advantageous to develop a pulsing method that does not huge drive currents needed so that you can use smaller components.

the Those skilled in the art of transducer design are aware of the supplied to a converter Current proportional to the speed of the face of this Transducer and thus the pressure (acoustic amplitude) that is in the medium is created into which is sent. To the apodization over the Can change the array it useful be to take advantage of this sensitivity of the converter drive current and at the same time maintain the relatively small size of the microbeamformer.

A The object of the present invention is a new system for apodization control of a controlled by a micro-beam former To create ultrasonic transducer arrays.

A Another object of the present invention is to provide a new System for apodization control of a controlled by a micro-beam former Ultrasonic transducer arrays to create the pull-up / pull-down devices Used in conjunction with multiple encoder supply voltages.

A Another object of the present invention is an apodization control to provide, for controlling the ultrasonic transducer several switchable Power sources used.

A Another object of the present invention is an apodization control creating one or more switchable power sources, to control the ultrasonic transducer for different lengths.

Around to accomplish these and other tasks an inventive system For Apodisierungssteuerung a Mikrostrahlformers several Mikrostrahlformerkanäle, the grouped into or associated with multiple microbeamformer patches, wherein each microbeamformer channel connects to a transducer includes a microbeamformer sending control and driving circuit To stimulate the transducer, a Mikrostrahlformerempfänger to to receive the transducer signals, and usually a delay unit, to delay the received transducer signal. The microbeamformer transmitter in each patch are connected to a common power supply node connected, but have their own circuits for controlling the timing. A mainframe beamformer has several mainframe channels one mainframe receiver each and a mainframe transmitter for transmitting a pulsed voltage. each Microbeamformer patch is, for example, one with the common Node of the patch connected cable, with a corresponding mainframe channel connected so that the mainframe receiver receives signals from the patch of microbeamformer receiver data paths feeds.

It There are several ways that the objects of the present invention to achieve either the creation of individual supply voltage connections to the Microbeamformer patches or creating custom control electronics provide power to / from each connected converter. The first method uses mainframe transmission drive units to to supply each patch with a different high voltage supply, the then it uses the individual transducers within this patch to bring different tensions. In the second procedure is a number of variable high voltage supplies in the mainframe assigned (separately and additionally to the mainframe transmission drive units), which are provided with one or more several of the microbeamformer patches are connected. A third Method uses a single dedicated high voltage power supply for all Microbeamformer patches, but sees to the control of the amplitude of the sent acoustic Waveform different current drive outputs per patch or transducer before. Finally, a fourth method uses a single, dedicated high voltage power supply for all microbeamformer patches and a single current drive output, however, the Power supply duration variable to the transducers, varying amounts to the transducers to supply electrical energy and thus to stimulate different acoustic amplitudes. These Procedures can used and implemented individually or in various combinations become a wealth different microbeamformer transmitter configurations with different drive capabilities to achieve. Every procedure is fulfilled the object of the invention, a Apodisierungssteuerung of ultrasonic transducer arrays to create, as summarized below.

The first method of applying apodization to micro-beamformed arrays uses the mainframe transmit drive units in the mainframe beamformer to provide each patch with a different high voltage power supply to drive each transducer. Timing control circuitry in each microbeamformer channel determines when the associated microbeamformer transmitter within the patch excites the transducer. The mainframe transmitter channel voltage, and thus the patch supply voltage, can be arbitrarily varied in this configuration because the mainframe transmitters are designed to provide a wide range of output voltages. The transmitter in each mainframe channel may be configured to provide a unipolar pulse for the duration of each transmit burst through the microbeamformer transmitters so that the pulses driven by the microbeamformer transmitters have an amplitude corresponding to the unipolar pulse from the mainframe channel. In this way, the mainframe transmitters become a variable voltage supply for the patch of transmitters in the microbeamformer.

One The intricate detail of this first procedure is the separation the broadcast events inherent have a high voltage, and the receiving events inherently a have low voltage. More specifically, to avoid transmitter noise contaminate the receive data path are between the microbeamformer transmitters and the cable and between the cable and the mainframe transmitters Diodes provided. Furthermore, can both in the output path from the microbeamformer receivers as also in the input path of the mainframe receiver protective devices such as switches be provided to the receiver to protect, when the transmitters are in operation.

By having one Mainframe transmitter for every patch is an independent one Supply voltage is provided, each patch can have different amplitude waveforms send and thereby for a to ensure improved shaping of the transmitted beam.

at another embodiment According to the invention, the patches are grouped into a plurality of clusters, wherein each cluster preferably comprises a plurality of patches. microbeamformer are then transferred from the mainframe a variety of individually adjustable power supplies (or mainframe transmitters) powered, and each cluster is, for example via a cable, with a corresponding one Energy supply connected. The supply voltage supplied to each cluster is independent adjustable or adjustable, for example, to a different Tension for every pulse repetition interval.

Even though the transmitters in each microbeamformer patch do not like the one above Embodiment of a special energy supply, become clusters microbeam shaper patches from a common power supply powered by an appropriate assignment of the microbeamformer patches to cluster the shape of the transmitted beam effectively and favorably can be controlled. Principal Advantage of this embodiment is the elimination of the diodes and switches, without the Number of cables required to power the various patch transmitters increased dramatically.

A direct extension of this embodiment consists of high voltage switch (or other switch means) into the Mikrostrahlformersender which selectively from a small number of mainframe powered high voltage rails. The is called, instead of pooling the patches or microbeamformer channels to one can use common high voltage power supply, any micro-beam former channel one or more high voltage switches included to one out select a small number of busbars. The choice of which track to use, and thus the applied drive voltage can Channel for Channel and for each pulse repetition interval be different.

at a third embodiment of the invention the drive units of the microbeamformer transmitter specially designed for this purpose be a particular converter with a variable current source instead as a voltage source to control. Unlike mainframe stations, who need to be able to Many different types of converters can control the Microbeamformer transmitter for it be designed to optimally and efficiently control a special converter. Therefore, it is possible multiple switchable current sources and sinks in each microbeamformer transmitter to use to drive the transducer, with larger currents greater acoustic Amplitudes and smaller currents cause smaller acoustic amplitudes from the transducer. These apodization methods can be done by looking for all microbeamformer channels uses a single common high voltage power supply. Furthermore let yourself the apodization control by selecting special source and sink currents reach easily on any microbeamformer channel, rather than in Grouped patches or patch clusters.

This embodiment of the invention comprises a plurality of switchable current sources, each comprising both a series switch and a pull-up device as well as meh rere switchable current sinks, which in turn each include a series switch and a pull-up device. Such a configuration of switchable current sources and sinks is known to those skilled in the art as Current Mode Analog to Digital Converter (DAC). The aforementioned pull-up devices may be PMOSFETs (also known as PMOS) devices that are biased to provide constant currents from the high voltage power supply to the converter. The PMOSFET devices may also be reverse biased to function as switches, or a separate PMOSFET device may be associated in series to perform the switch function. Similarly, the pull-down devices may be NMOSFETs (also known as NMOS) devices that are biased to provide constant currents from the transducer to ground (or a negative supply supply connection). The NMOS FET devices may also be reverse biased to function as switches, or a separate NMOSFET device may be serially associated to perform the switch function.

the It is known to those skilled in the art that the current carrying capacity of PMOS and NMOS devices proportional to their width and also behaves is a function of the applied gate bias voltage. In this embodiment would the Mikrostrahlformersender preferably a small number of PMOS and NMOS devices that selectively (by their gate bias) enable to control different drive currents from each transducer. For a maximum efficiency allowed the pull-up and pull-down devices are not simultaneously conducting but other less efficient modes of operation are possible.

in the Normal operation of a preferred embodiment becomes a selected subset activated by PMOS devices to drive the converter. The Number of activated components, and thus the available drive current, can be controlled individually on each microbeamformer channel. Preferably, the PMOS devices become for the Duration approximately a quarter wavelength of the acoustic signal to be activated. Subsequently, will a selected one Subgroup of NMOS devices for the Duration approximately a quarter wavelength of the acoustic signal to be activated to the converter discharged. It should be noted, however, that if the selected pull-up and pull-down currents the duration of the pull-up and pull-down events possibly unequal. The voltage developed at the converter is while a function of the applied drive current and the capacity of the converter, In general, however, it will be a rising ramp to some tension followed by a sloping ramp. The slope of these ramps is defined by the drive current and the converter capacitance.

A Main component of this embodiment the invention is that the drive currents during the pull-up and pull-down events are programmable, but the duration of these events (for a given desired acoustic frequency). That is, to different apodization levels over the Achieve array across each of the microbeamformer channels can be different streams for one deliver predetermined pull-up and pull-down durations that are the same for all channels is. The time to which the channels the converters drive, hangs from the desired Delay, and that supplied to the transducers Electricity depends on the desired Apodization off.

A direct extension of the above embodiment is still one another embodiment of the Invention to provide on each Mikrostrahlformerkanal a pull-up and a pull-down device is assigned to the Converter for To control time spans, depending on the desired apodization on the Vary across the array. In this approach of pulse width modulation the time span varies for the the pull-up and the Pull down components are activated, whereby the total energy supplied to the transducer is controlled. The resulting acoustic waveform amplitude will approximate be proportional to the width of the applied current pulses.

The Main differences between this embodiment and the previous one Multiple stream embodiment consist of the way the microbeamformer transmitters are controlled. In the multiple current embodiment the apodization function determines the current setting, however the pulse-up and pulse-down sequence (despite from channel to channel different start time of this sequence) all channels is equal to. In this embodiment determines the Apodisierungsfunktion the pulse width of the up and Down events, but with the pull-up and pull-down currents at all channels are equal (and the start time of this sequence from channel to channel is also different). There are, of course, tradeoffs the timing complexity between these embodiments, against the differences in the complexity (size) of the high voltage source weigh are.

For the expert It should be obvious that each of these embodiments novel paradigms concerning power supply connection, design of high voltage driving circuits and methods of timing represent the control units that are in different different Configurations could be combined. Depending on the application and implementation restrictions may be one of these various embodiments or combinations of which optimal or desirable be. This invention should be understood to include both the individual ones described embodiments as well as any combinations thereof are covered.

The Invention and its other objects and advantages can be best understood by reference to the following description, which to be seen in conjunction with accompanying drawings, wherein the same Reference signs denote like elements. Show it:

1 the schematic representation of a first embodiment of a Mikrostrahlformerteils an ultrasonic transducer, the apodization control used according to this invention;

2 a schematic representation of a second embodiment of a Mikrostrahlformerteils an ultrasonic transducer, which uses a Apodisierungssteuerung according to this invention;

3 a diagram showing a possible grouping of microbeamformer patches in clusters according to the second embodiment of this invention;

4A a schematic representation of a first embodiment of a circuit for controlling the drive voltage according to this invention;

4B a schematic representation of a second embodiment of a circuit for controlling the drive voltage according to this invention;

5 a schematic representation of a first circuit for controlling the drive current according to this invention;

6 a schematic representation of a second circuit for controlling the drive current according to this invention;

7 a schematic representation of a third circuit for controlling the drive current according to this invention;

8th a schematic representation of a micro-beam forming part of an ultrasonic transducer according to the prior art.

following Various methods for Apodisierungssteuerung a micro-beam former an ultrasonic transducer described. These methods have that common goal, the ability to Forming the transmission beam improve by adding each transducer or a variety of transducers in a microbeamformer patch supplied Control voltage or the supplied drive current adjusted becomes. The procedures can independently from each other or in the possible Scope be used in combination with each other.

In a first embodiment of a system for apodization control of a microbeamformer, shown in FIG 1 , the voltage applied to each microbeamformer patch is adjustable. A mainframe beamformer 10 The ultrasound imaging system includes a plurality of mainframe channels 12 where each mainframe channel 12 a mainframe station 14 and a mainframe receiver 16 includes. A coaxial cable 18 connects every mainframe channel 12 with a corresponding subarray beamformer, here also as a microbeamformer patch 20 designated. Every patch 20 includes a plurality of microbeamformer channels 22 each of which has a microbeamformer transmitter 24 , a circuit for controlling the transmitter timing 24A , a converter 26 by a signal from the microbeamformer transmitter 24 is driven, a Mikrostrahlformerempfänger 28 , the signals from the converter 26 receives, and a delay element 30A includes. Instead of a coaxial cable 18 For example, other cables and electronic interconnect components known to those skilled in the art may also be used. For the microbeamformer transmitter 24 usually is often a delay element 30B intended.

Every mainframe station 14 leads the respective patch 20 over the cable 18 a supply voltage to. Thus, both the mainframe station 14 as well as the mainframe receiver 16 over a node 32 with the cable 18 connected. By each of the mainframe stations 14 with a corresponding patch 20 may transmit the microbeamformer 24 in the microbeamformer channels 22 every patch 20 an individually adjustable voltage may be applied to thereby control the microbeamformer channels 22 in every patch 20 to allow and any desired shaping of the converters 26 in every patch 20 To ensure generated transmission beam.

During operation, for at least the duration of each transmit burst, a unipolar pulse from the mainframe transmitters 14 to the microbeamformer patches 20 sent, more specifically to the Mikrostrahlformersendern 24 in every microbeamformer patch 20 , The voltage of the unipolar pulse is intermittently transmitted through the microbeamformer transmitter 24 in every microbeamformer patch 20 fed to unipolar pulses to the transducers 26 in every microbeamformer patch 20 to create. The time at which the microbeamformer transmitter 24 the transducers 26 high or low, and the number of such pulses will be in each microbeamformer channel 22 clearly and individually controlled, however, taking the amplitude of the pulses from that through the mainframe transmitter 14 supplied voltage is set for all micro-beamformer transmitters 24 in a patch is the same. Thus, both the mainframe transmitters carry 14 as well as the microbeamformer transmitter 24 to the drive signals for the converters 26 at.

Both in the mainframe channels 12 as well as in the microbeamformer patches 20 are additional diodes 34 connected in series with the transmitter power branch to the mainframe transmitter 14 and the microbeamformer transmitter 24 to isolate from the signal path during receive operation. Although, as in 1 shown a sentence dio the 34 in every microbeamformer patch 20 is arranged to all microbeamformersender 24 In this microbeamformer patch, during isolation from the signal path, several sets of diodes could alternatively be used. A second set of diodes 34 is in every mainframe channel 12 between the mainframe transmitter 14 and the node 32 arranged. Instead of diodes 34 For example, other isolation devices known to those skilled in the art may also be used.

Both in the mainframe channels 12 as well as in the patches 20 are switches in the receiver branch 36 provided to the input of the mainframe receiver 16 and the output of the microbeamformer receiver 28 with a high voltage protection, so that they can withstand transmission events. Although, as in 1 shown in each microbeam former channel 22 in every patch 20 a switch 36 provided could be in the patches 20 alternative switch arrangements may be used as long as the output of the microbeamformer receivers 28 is provided with a high voltage protection.

Another embodiment of a system according to the invention for Apodisierungssteuerung has a simpler structure than that in 1 shown embodiment, since it requires no additional diodes and no input / output protection, such as switches. Although the use of the diodes and receiver output protection offers advantages over prior art apodization control methods, it means additional parts and control complexity.

Now referring to 2 This embodiment does not see individual apodization for each patch 20 but the independent apodization of several discrete groups or clusters 38A . 38B of patches 20 (of which in 2 only two are shown). In this embodiment, the patches are 20 into several clusters 38A . 38B grouped, with at least one and possibly all clusters 38A . 38B several patches 20 to have. Every cluster 38A . 38B has a supply voltage 40A . 40B that allows the transmission voltage of the patches 20 in this cluster 38A from the transmission voltage of the patches 20 in the other clusters 38B is independent. For the sake of clarity, is in 2 just a microbeamformer channel 22 in every patch 20 however, it should be understood that each patch 20 several microbeamformer channels 22 includes (such as in 1 shown).

A coaxial cable 42 connects every supply voltage 40A . 40B with a knot 44 of the corresponding cluster 38A . 38B Using the microbeam shaper transmitters 24 every patch 20 hardwired in this cluster. Instead of a coaxial cable 42 Other cables or electrical connection components may also be used.

This embodiment affects the IC architecture of the micro-beamformer in that it must be designed to provide multiple separate power supplies to the chips (but only one per patch), and that the separate power supplies must be arranged in such a way that a useful apodization is ensured. 3 For example, one possible arrangement illustrates how to map patches 20 to cluster 38 , wherein 16 chips are used to form integrated circuits 46 . 48 (the double lines represent the boundaries between the 16 integrated circuits). The 128 patches 20 are in eight clusters 38 grouped by numbers. The four ICs 46 in the two middle rows use all eight power supplies, while the remaining ICs 48 use less. If the supply voltage for each patch 20 When an input pin / pad is available, the ICs can 46 . 48 however, be identical in which case the allocation of the supply voltage to each patch 20 at the level of connection between the ICs 46 . 48 and the wiring can take place where adjustments are easier. Thus, in this embodiment, a number of dedicated power supplies are fixed to the clusters 38 each of which has at least one and preferably several patches 20 includes.

The supply voltages provided in the mainframe 40A . 40B may have any known design to the microbeamformer transmitter 24 to supply controllable energy.

Another embodiment of an apodization control system according to the invention has a small number of high voltage rails (e.g., two) provided to each microbeamformer transmitter. When the transmitter drives the associated transducer, it can be instructed to choose between these supplies. As in 4A shown are two high voltage rails (HV) 88 . 90 with a single PMOS pull-up device or transistor 92A connected. The HV rail 88 (referred to as HV1) has a higher voltage than the HV rail 90 (referred to as HV2). Between the HV rail 88 and the pull-up device 92A is a high voltage switch 94 switched while between the HV rail 90 and the pull-up device 92A a diode 96 is switched. The pull-up device 92A is at a node 98 with the converter 26 connected. A pull-up device or a transistor 92B is with the node 98 ver tied to the converter 26 to unload.

By setting HV2 to a voltage below HV1, each of the two power supplies can be selected by switching the per-element (or per patch) switch 94 is activated to produce unipolar pulses with amplitudes determined by the selected power supply. In one possible, functional embodiment, converters have 26 the lower HV2 supply is selected near the periphery of the transmit aperture. The diode 96 could also be a switch like the switch 94 however, would require additional circuitry to turn on the device. More than two HV supplies can be supported by running parallel to the switch 94 additional switches and associated supplies are involved.

Instead of connecting two HV rails to a single pull-up device, one via a switch and the other via a diode, as in 4A shown, one can for each HV rail 88 . 90 a separate pull-up device 92A use as in 4B shown. The pull-up components 92A act as a switch in this embodiment, so that no separate switch (element 94 in 4A ) required are.

The method of providing multiple voltage sources and switching between the voltage sources using a pull-up device, as in 4A is applicable in all cases where the Mikrostrahlformersender 24 be supplied with voltage. Thus, this method can be used in the power supply clustering methods described above with reference to FIG 1 - 3 were addressed. For example, two or more HV rail supplies may be provided for each patch to allow the voltage for that patch to switch between the HV supplies. In this way, per patch, each of the supply voltages for a particular transmit aperture can be. In addition, the multiple HV rail supplies can be sent to each microbeamformer transmitter 24 within a single patch 20 be provided so that you can converters 26 for transducers 26 each of the supply voltages for a particular transmit aperture can use.

In some embodiments of the invention, it is possible, in addition to or instead of providing control of the voltage to the microbeamformer transmitters 24 to the drive signals to the converters 26 that of microbeam shaper transmitters 24 to regulate provided drive current. In conventional microbeamformers, only those of the microbeamformer transmitters are used 24 provided voltage regulated. However, by using a drive current model, the sensitivity of the transducers becomes 26 exploited for the electricity. That is, rather than the transducers 26 Driving with voltage excitation alone (with unlimited current) will cause the transducers 26 driven to the extent with a current that the voltages involved by the converters 26 can be tolerated. In this way, very small drive circuits can be created and into an integrated circuit near the transducers 26 to get integrated. In such highly integrated micro-beamformers, there is no extensive wiring between the drive circuits and the converters to be charged and discharged 26 required, which further improves the efficiency of the inventive micro-beam former.

Drive current circuits used in the invention generally include switchable current sources and sinks, which are a variation of that with the converters 26 allow supplied electricity. Since the input and output current of the converter 26 is approximately equal to the acoustic velocity, various acoustic signals can be synthesized by varying the driving current.

A first embodiment of a current-controlled ultrasound microbeamformer transmitter 24 is in 5 and comprises a digital / analog converter cell 50 with multiple switchable power sources, each a pull-up device 52 included, which is connected at one end to the input voltage and the other end with a corresponding switch 54 connected is. The switches 54 are over an output node 56 with the converter 26 connected. The converter 26 is highly capacitive and is therefore due to a capacitor 58 shown. The switches 54 are controlled in a binary fashion to provide up to eight different current outputs, allowing for eight different currents at the output node 56 be provided when the power outputs the pull-up devices 52 happen.

Given the capacity of the converter 26 The voltage generated across the load continues to grow when one of the pull-up devices 52 is activated. To the capacitor 58 To discharge, a plurality of switchable current sinks are provided, each current sink is a pull-down device 60 and a corresponding switch 62 includes. The current sinks are controlled to provide up to eight different discharge currents. To achieve optimum efficiency, the pull-up components should 52 and pull-down components 60 not be activated at the same time. The voltage at the output node 56 is a function of the cumulative charge transfer to and from the plate of the capacitor 58 and thus a radio tion of the currents 52 and 60 and the duration for which these components are activated to the node 56 head for.

The pull-up components 52 and pull-down components 60 may be high voltage MOSFET devices operating in saturation. The current through an "on" MOSFET is proportional to its width 50 Thus, three high-voltage PMOSFET pull-up devices are implemented 52 required, preferably with different widths, such as the widths 1x, 2x and 4x, as well as three NMOSFET pull-down devices 60 with corresponding widths (1x, 2x and 4x). Alternatively, multiple pull-up or pull-down devices may be used in parallel with common gate terminals to provide these different drive currents. The way how the gate electrodes of the MOSFET devices 52 . 60 The manner in which similar pull-up or pull-down currents are obtained would be readily apparent to one skilled in the art. It would also be apparent to one skilled in the art that the series switches 54 . 62 could be eliminated when the gate electrodes of the current source / sink MOSFET devices 52 . 60 itself would be controlled to the flow of current to / from the node 56 to disable. In the converter cell 50 For example, other pull-up and pull-down devices known to those skilled in the art (eg, bipolar transistors) could also be used.

The previous construction of the converter cell 50 , which uses drive current control circuits, is particularly advantageous for controlling ultrasonic transducers, and in particular micro-beamformer transducers, because the repeater cells 50 take up less space than comparable voltage control circuits (which require large source / sink currents) and have better performance constraints. Another advantage is that the acoustic response is much more predictable because there is no tuning network and cable capacity (as in normal wired converters) between the driver and microbeamformer transducers.

Another modification of drive current control circuits is based on the recognition that all of the converters 26 provided and thus transmitted to the body energy is not only a function of the driving current but also the time. Consequently, it is possible to use a high-voltage converter cell as described above with reference to FIG 5 described converter cell 50 to use pulse width modulation controls to generate different transmission waveforms. The concept of pulse width modulation can also be used with a single current source / current sink pair where the times at which these currents are activated can control the output acoustic amplitude.

In 6 is a converter cell employing pulse width modulation 70 shown. The converter cell 70 includes a single pull-up device 72 and a single pull-down device 74 , which are each supplied with a constant current and activated for a different duration. This will be the one with the parent node 76 supplied transducers with different current pulses that can synthesize different waveform amplitudes or shapes.

A control computer or processor 78 is provided to specify events for the control changes and events for each line and frame of the imaging operation, and which may optionally also generate such events. The control computer 78 directs the required event commands to a timing generator 80 and optionally to the mainframe stations. About the power supply rails, the mainframe transmitter of the converter cell 70 provide a complete waveform, as in any of the embodiments described above. As known to those skilled in the art, the ultrasound imaging system may also include other components for generating event commands to provide a desired transmit waveform.

The timing generator 80 sets the number of pulses in each burst, the pulse repetition frequency, the pulse width, and the delay (used for focusing) and generates an appropriate timing signal representative of the converter cell 70 caused to generate the desired waveform from the power supply upon receipt of the timing signal.

More specifically, the timing generator generates 80 a timing signal or pulse width modulation signal for the switches 82 . 84 , The extent to which the switch 82 is on or off, ie the duration for which the switch 82 is turned on, determines the width of the current pulse from the pull-up device 72 , The extent to which the switch 84 is on or off, ie the duration for which the switch 84 is turned on, determines the width of the current pulse through the pull-down device 72 to earth.

The converter cell 70 comes with a single pull-up device 72 and a single pull-down device 74 shown. As in 7 it is also possible to show a converter cell 86 with multiple pull-up and pull-down components that construct multiple different currents deliver. So if MOSFET devices than the pull-up devices 72 and the pull-down components 74 are used, the widths of the MOSFET devices are different, for example, x, 2x as shown. In this way, the various combinations of opening and closing provide the switch 82 . 84 different currents.

Controlling the timing of the pull-up and pull-down devices 72 . 74 if these components 72 . 74 To drive the converter is complicated, but can be determined by a specialist. The capacitive load should be appropriately controlled from one channel to the next so that uniform acoustic outputs are achieved.

The above with reference to the 4 - 6 addressed current-mode scaling / Apodisierungsverfahren are suitable when the output of the Mikrostrahlformersenders 24 voltage generated does not reach the high voltage supply rail (the HV rail). As the output voltage approaches that of the HV rail, the PMOSFET pull-up devices get stuck 72 out of saturation and finally listen to conduct electricity when the HV rail is the voltage at the converter 26 reached. Thus, it is a disadvantage that the methods of current modulation and current pulse width modulation are inefficient when the converter voltage charges the entire distance to the HV rail. To maximize the output of acoustic energy, a charge that is as close as possible to that of the HV rail is desirable. Since there is inherently some uncertainty in both the drive current and the actual element load, it is very difficult to obtain maximum acoustic output power and still have good control over the transmit waveforms.

The above with reference to 5 - 7 Current mode methods discussed above are sensitive to element load and drive variations, resulting in operational disadvantages, and are therefore not suitable for all applications. To overcome these disadvantages, the previously in the 1 - 4 presented methods for current (voltage) supply control can also be used in conjunction with the above-mentioned current mode method. For example, the pull-up device could 92A and the pull-down device 92B in the double HV rail circuit 4A the power sources 72 and 74 out 7 to implement. The gate electrodes of the pull-up device 92A and the pull-down device 92B , in 4 labeled UP and DOWN could be driven with appropriate pulse width modulated signals to the converter 26 supply with fixed source and sink currents for a certain period of time. If the pulse duration is not long enough to reach the output node 98 on the selected HV rail (either 88 or 90 ), the pulse width modulation methods can be used. On the other hand, if the pulse duration is long enough to reach the output node 98 Fully charge up to the selected HV rail, power supply methods (clustering, etc.) can be used.

Claims (24)

A system for apodization control of a microbeamformer, comprising: a mainframe beamformer ( 10 ) with several mainframe channels ( 12 ), each of the mainframe channels mentioned being a mainframe receiver ( 16 ) and a mainframe transmitter ( 14 ) to transmit a pulsed power supply voltage; several microbeamformer patches ( 20 ), wherein each of said microbeamformer patches comprises a plurality of microbeamformer channels ( 22 ), each of said microbeamformer channels comprises a transducer ( 26 ), a microbeamformer transmitter ( 24 ) and a control circuit for driving said converter, a microbeamformer receiver ( 28 ) for receiving signals from said converter ( 26 ) and a delay element ( 30A ) for delaying the received transducer signals, and wherein said microbeamformer transmitters ( 24 ) in each of said microbeamformer patches ( 20 ) with a common node ( 32 ) are connected; several separate electrical connections ( 18 each of said ports communicating with said common node in each of said microbeamformer patches with a corresponding one of said mainframe channels ( 12 ), so that said mainframe transmitter ( 14 ) in said mainframe channel ( 12 ) the pulsed power supply voltage across said terminal all of said micro beamformer transmitters ( 24 ) in said microbeamformer patch ( 20 ); Isolation agent ( 34 ) to the said microbeamformer transmitter ( 24 ) and the mentioned mainframe transmitters ( 14 ) when said microbeamformer receivers ( 28 ) and the mentioned mainframe receivers ( 16 ) are in operation; and protective agents ( 36 ) to the said microbeamformer receivers ( 28 ) and the mentioned mainframe receivers ( 16 ), when said microbeamformer transmitters ( 24 ) and the mentioned mainframe transmitters ( 14 ) are in operation. A system according to claim 1, wherein said isolation means ( 34 ) between each of said ports and said mainframe sen of the ( 14 ) in the corresponding one of the mainframe channels ( 12 ) and between each of said ports and said common node ( 32 ) of the corresponding one of said microbeamformer patches ( 20 ) are arranged. A system according to claim 1, wherein said isolation means ( 34 ) Comprise diodes. A system according to claim 1, wherein said protection means ( 36 ) between each of said ports and said mainframe receiver ( 16 ) in the corresponding one of the mainframe channels ( 12 ) and between each of said ports and said microbeamformer receivers ( 28 ) in each of said microbeamformer channels ( 22 ) are arranged. A system according to claim 1, wherein said protection means ( 36 ) Comprise switches. A system according to claim 1, wherein said ports ( 18 ) Cables. The system of claim 1, wherein said mainframe transmitters ( 14 ) in each of the mainframe channels ( 12 ) are arranged to emit a unipolar impulse through said microbeamformer transmitters for the duration of each transmission burst ( 24 ) in the corresponding one of said microbeamformer patches 20 transferred to. A system according to claim 7, wherein said mainframe transmitters ( 14 ) the power supply voltage for each of said microbeamformer transmitters ( 24 ) in the corresponding one of said microbeamformer patches 20 and thereby provide each of said transducers ( 26 ) in the corresponding one of said microbeamformer patches ( 20 ) to define supplied amplitude. A system according to claim 8, wherein said mainframe transmitters ( 14 ) are adapted to vary the transmitted voltage. A system according to claim 1, wherein said microbeamformer transmitter ( 24 ) in at least one of said microbeamformer channels ( 22 ) Comprising: a plurality of switchable power sources, each of said power sources comprising a pull-up device ( 52 ) adapted to receive the pulsed power supply voltage, and one between said pull-up device ( 52 ) and said converter ( 26 ) of said microbeamformer channel ( 22 ) switched switch 54 includes; and a plurality of switchable current sinks, wherein each of said current sinks is a pull-down device ( 60 ) and one between said pull-down device ( 60 ) and grounded switches ( 62 ) and wherein said pull-down devices ( 60 ) are adapted to the said converter ( 26 ) via the mentioned switches ( 62 ) to unload. The system of claim 10, wherein said pull-up devices ( 52 ) Are PMOSFET devices that are operated in saturation, and wherein said PMOSFET devices have different widths and provide a current proportional to the width. The system of claim 10, wherein said pull-down devices ( 60 ) NMOSFET devices are those that have different widths and deliver a current proportional to the width. A system according to claim 1, wherein said microbeamformer transmitter ( 24 ) in at least one of said microbeamformer channels ( 22 ) Comprising: at least one switchable power source, each of said at least one power source being a pull-up device 72 which is adapted to receive the pulsed power supply voltage, and one between said pull-up device 72 and said converter ( 26 ) of said microbeamformer channel ( 22 ) switch ( 82 ); at least one switchable current sink, each of said at least one current sink being a pull-down component ( 74 ) and one between said pull-down device ( 74 ) and grounded switches ( 84 ) and wherein said pull-down device ( 74 ) is adapted to the said converter via said switch ( 84 ) to unload; and control means ( 78 ) for controlling said switches in each of said at least one current source and said at least one current sink to pulse width modulate the transmit waveform generated by said microbeamformer transmitter. A system according to claim 13, wherein said control means comprises a timing generator (10). 80 ) for generating signals for controlling said switch in each of said at least one current source and said at least one current sink and a control computer for controlling said timing generator. The system of claim 13, wherein said at least one power source comprises a plurality of power sources and said pull-up components These devices are PMOSFET devices that operate in saturation and have different widths and provide a current proportional to the width. The system of claim 15, wherein said at least a current sink comprises a plurality of current sinks and said pull-down devices in said current sinks NMOSFET devices are in saturation be operated and have different latitudes and a current deliver proportionally to the width. The system of claim 16, wherein said control means a timing generator for generating signals for control said switch in each of said power sources and power sinks and a control computer for controlling said timing generator include. A system for apodization control of a microbeamformer, comprising: a plurality of microbeamformer patches ( 20 ), each of said microbeamformer patches ( 20 ) a plurality of microbeamformer channels ( 22 ), each of said microbeamformer channels ( 22 ) a converter ( 26 ), a microbeamformer transmitter ( 24 ) and a control circuit for driving said converter, a microbeamformer receiver ( 28 ) for receiving signals from said converter ( 26 ) and a delay element ( 30A ) for delaying the received transducer signals, and wherein said microbeamformer patches ( 20 ) into several clusters ( 38A , ...) are grouped together so that each of the named clusters ( 38 ) several of said microbeamformer patches ( 20 ), and said microbeamformer transmitters ( 24 ) each of said clusters with a common node ( 44 ) are connected; a mainframe beamformer with several individually adjustable power supplies ( 40A . 40B ) and several mainframe channels ( 16 ), each of said channels comprising a mainframe receiver; first connection means ( 18 ) to connect said microbeamformer receivers in each of said microbeamformer patches to a corresponding one of said microbeamformer channels ( 16 ) connect to; and second connection means ( 42 ) to each of the named clusters ( 38 ) with a corresponding one of said power supplies 40 connect to. The system of claim 18, wherein said first and second connection means comprise cables. The system of claim 18, wherein each of said Cluster supplied Power supply voltage independent is adjustable. The system of claim 20, wherein each of said Cluster supplied Power supply voltage for each pulse repetition interval to a different voltage is adjustable. The system of claim 18, wherein said microbeamformer transmitter in at least one of said microbeamformer channels comprises: a plurality of switchable current sources, each of said current sources having a pull-up device ( 52 ) adapted to receive the pulsed power supply voltage, and one between said pull-up device ( 52 ) and said converter ( 26 ) of said microbeamformer channel ( 22 ) switch ( 54 ); and a plurality of switchable current sinks, each sinking a pull-down device ( 60 ) and one between said pull-down device ( 60 ) and grounded switches ( 62 ) and wherein said pull-down devices ( 60 ) are adapted to the said converter ( 26 ) via the mentioned switches ( 62 ) to unload. The system of claim 22, wherein said pull-up devices PMOSFET devices are those that are operated in saturation, and wherein said PMOSFET devices have different widths and deliver a current proportional to the width. The system of claim 22, wherein said pull-down devices NMOSFET devices are those that have different widths and one Supply current proportional to the width.